and intestines, irritated by the presence of a substance foreign and noxious to the digestive process, are stimulated into action and cause an augmented quantity of secretion to be poured forth, and the folds of the colon are filled with fluid fouled by dissolved fecal matter, which is partially absorbed ere evacuation can occur.
Purgatives in medicine are drugs which act as described, and they are divided according to their supposed peculiar properties. Thus there are cholagogues, that increase the flow of bile, and intestinal purgatives, that act on the intestinal secretion, e. g., calomel ; or that increase peristaltic action, e. g., aloes and cascara. Again there are drastic purgatives or cathartics, e. g., croton oil ; and mild aperients, e. g., compound licorice powder and senna.
Each application of the remedy finds the alimentary tract less able to contend against its presence, and, in order to obtain the desired effect in future, larger doses are necessary, more of the digestive fluids of the body are wasted, and the cathartic habit becomes as dangerous as continued indulgence in morphine. By it digestive juices are drawn upon to excess, digestion is rendered difficult, if
